JS map return object

Question

I got this array   var rockets           country  Russia   launches 32          country  US   launches 23          country  China   launches 16          country  Europe ESA    launches 7          country  India   launches 4          country  Japan   launches 3        What do I need to do to return an array mapped  that adds 10 to each      launches   value   here my first approach   var launchOptimistic   rockets map function elem        return  elem launches 10       return  elem country  elem launches 10         console log launchOptimistic

User · Answer

You re very close already  you just need to return the new object that you want  In this case  the same one except with the launches value incremented by 10    x000D   x000D  var rockets     x000D        country  Russia   launches 32    x000D        country  US   launches 23    x000D        country  China   launches 16    x000D        country  Europe ESA    launches 7    x000D        country  India   launches 4    x000D        country  Japan   launches 3   x000D     x000D   x000D  var launchOptimistic   rockets map function elem    x000D    return   x000D      country  elem country  x000D      launches  elem launches 10  x000D       x000D      x000D   x000D  console log launchOptimistic   x000D   x000D   x000D

User · Answer

Use  map without return in simple way  Also start using let and const instead of var because let and const is more recommended    x000D   x000D  const rockets     x000D        country  Russia   launches 32    x000D        country  US   launches 23    x000D        country  China   launches 16    x000D        country  Europe ESA    launches 7    x000D        country  India   launches 4    x000D        country  Japan   launches 3   x000D     x000D   x000D  const launchOptimistic   rockets map elem   gt    x000D      x000D      country  elem country  x000D      launches  elem launches 10 x000D       x000D      x000D   x000D  console log launchOptimistic   x000D   x000D   x000D

User · Answer

map rockets and add 10 to its launches    x000D   x000D  var rockets     x000D        country  Russia   launches 32    x000D        country  US   launches 23    x000D        country  China   launches 16    x000D        country  Europe ESA    launches 7    x000D        country  India   launches 4    x000D        country  Japan   launches 3   x000D     x000D  rockets map  itm    gt    x000D      itm launches    10 x000D      return itm x000D     x000D  console log rockets  x000D   x000D   x000D    If you don t want to modify rockets you can do   var plusTen      rockets forEach  itm    gt        plusTen push   country   itm country   launches   itm launches   10

User · Answer

If you want to alter the original objects  then a simple Array forEach will do   rockets forEach function rocket        rocket launches    10        If you want to keep the original objects unaltered  then use Array map and copy the objects using Object assign   var newRockets   rockets forEach function rocket        var newRocket   Object assign     rocket       newRocket launches    10      return newRocket

[javascript] JS map return object

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